A variety of harsh or extreme environments may disrupt a microelectronic device from operating normally. High electric and magnetic fields or ionizing radiation, for example, may create such an environment. Typically, a microelectronic device may be designed or equipped in order to properly work in a particular environment. Such designs may include incorporating protective measures within the device's substrate, such as electrical isolation. Additional or alternative designs use a protective shield that blocks potentially harmful electronic or magnetic fields.
One type of shield, in particular, that is used to protect microelectronic devices from stray external magnetic fields is a magnetic shield. In general, a device will use two shields for protection: one positioned below the device and another positioned above the device. These shields generally comprise high permeability materials that both absorb magnetic forces and redirect the forces away from the semiconductor device. Current magnetic shields, however, are not effective at blocking both direct current (DC) and alternating current (AC) magnetic fields.